Use N = 14 u, ammonia = 17 u, urea = 60 u and uric acid = 168 u…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Use u, ammonia u, urea u and uric acid u.
- What per cent of the mass of ammonia is nitrogen?
- What per cent of the mass of urea is nitrogen?
- What per cent of the mass of uric acid is nitrogen?
- Which waste carries the most nitrogen in each gram?
Need a reminder? The key ideaShow
The three nitrogenous wastes are ammonia (one nitrogen atom in a molecule), urea (two) and uric acid (four). Ammonia is the most toxic and needs the most water. Uric acid is the least toxic and leaves as a paste. Ammonotelic animals are bony fishes, aquatic amphibians and aquatic insects. Ureotelic animals are mammals, many terrestrial amphibians and marine fishes. Uricotelic animals are reptiles, birds, land snails and insects. Use u, ammonia u, urea u and uric acid u.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. Masses in u: N , ammonia , urea , uric acid .
Plan. Share of nitrogen .
Step 1. Ammonia. .
Step 2. Urea. .
Step 3. Uric acid. .
Step 4. The most nitrogen. Ammonia, with .
Answer: ; ; ; ammonia.
Check. Uric acid has the most nitrogen atoms in a molecule but the smallest share by mass, because the molecule is so heavy.
Source. With the exact atomic masses the shares are , and .
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